Key parameters at a glance

A radius of 0.34 Earth radii
A mass of 0.02 Earth masses
Surface gravity around 0.18 g
An orbital period of 25.262 days
Semi-major axis 0.1900 AU
Distance from Earth 1,956.94 light-years
Earth Similarity Index 0.616
Travel time at Voyager 1 speed 34,510,564 years

Context from the literature

PSR B1257+12 b, alternatively designated PSR B1257+12 A, also named Draugr, is an extrasolar planet approximately 2,300 light-years (710 pc) away in the constellation of Virgo. The planet is the innermost object orbiting the pulsar Lich, making it a pulsar planet in the dead stellar system. It is about twice as massive as the Moon, and is listed as the least massive planet known, including among the planets in the Solar System.

Excerpted from Wikipedia · full article

2 siblings around PSR B1257+12

PSR B1257+12 b shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
PSR B1257+12 b this	Rocky Terrestrial	0.34	0.02	25.262	—	1994
PSR B1257+12 c	Super-Earth	1.91	4.30	66.542	—	1992
PSR B1257+12 d	Super-Earth	1.80	3.90	98.211	—	1992

PSR B1257+12 b Planet Profile

Physical Specs

Radius

0.34 R⊕

Radius (Jupiter)

0.030 R♃

Mass

0.02 M⊕

Mass (Jupiter)

0.000 M♃

Density

2.85 g/cm³

Surface Gravity

0.18 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.616

HZ Position Unknown

Controversial No

Discovery

Year 1994

Method Pulsar Timing

Facility Arecibo Observatory

Telescope 305 m Arecibo Radio Telescope

Size rank in cohort

Rank by radius

#569of 570

top 99.6%

This planet

0.34R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-37 b 0.31 R⊕ Kepler-37 e 0.37 R⊕ Kepler-879 c 0.40 R⊕

Metric	Earth	PSR B1257+12 b	Jupiter
Radius (R⊕)	1.00	0.34	11.21
Mass (M⊕)	1.00	0.02	317.83
Density (g/cm³)	5.51	2.85	1.33
Surface Gravity (g)	1.00	0.18	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	0.020 M⊕	Direct mass measurement (not derived).
Minimum mass (M sin i)	0.015 M⊕	Lower bound from radial-velocity fitting.

Percentile among Rocky Terrestrial cohort

Radius 0.338 R⊕ · percentile 0 / cohort 570

Mass 0.020 M⊕ · percentile 0 / cohort 570

Orbital period 25.26 d · percentile 95 / cohort 567

Distance 600.00 pc · percentile 73 / cohort 566

ESI 0.616 · percentile 79 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

25.262 days

Semi-major axis

0.1900 AU

Eccentricity

0.000

Inclination

50.00 °

Year Length

A year here lasts approximately 25.26 Earth days (6.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1900 AU.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.616

0 = alien, 1 = Earth-identical

Discovery Paper

Primary reference

Wolszczan 1994

Instrument

Arecibo Radio Reciever

Publication

1994-04

Observation locale

Ground

Host System: PSR B1257+12

Spectral Class

Unknown

Effective Temperature

—

Estimated Age

3.00 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

—

Stellar Mass

1.400 M☉

Metallicity [Fe/H]

—

Distance

600.00 parsec

Light-years 1,956.94 ly

V-band magnitude

— mag

Voyager-speed travel 34,510,564 yr

Wikipedia → Image: Wikimedia Commons · Aldaron, a.k.a. Aldaron · CC BY-SA 3.0

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